import base64js from "./base64";

// Crypt 
class Crypt {
    /**
     * Converts a JS string to an UTF-8 uint8array.
     *
     * @static
     * @param {String} str 16-bit unicode string.
     * @return {Uint8Array} UTF-8 Uint8Array.
     * @memberof Crypt
     */
    static stringToArrayBufferInUtf8(str) {
        // if not browser env, then require node.js's util. otherwise just use window's
        const TextEncoder = (typeof window === 'undefined') ? require('util').TextEncoder : window.TextEncoder
        // always utf-8
        let encoder = new TextEncoder()
        return encoder.encode(str)
    }

    /**
     * Converts an UTF-8 uint8array to a JS string.
     *
     * @static
     * @param {Uint8Array} strBuffer UTF-8 Uint8Array.
     * @return {String} 16-bit unicode string.
     * @memberof Crypt
     */
    static utf8ArrayBufferToString(strBuffer) {
        // if not browser env, then require node.js's util. otherwise just use window's
        const TextDecoder = (typeof window === 'undefined') ? require('util').TextDecoder : window.TextDecoder
        let decoder = new TextDecoder('utf-8')
        return decoder.decode(strBuffer)
    }

    /**
     * crypt a utf8 byteArray to base64 string
     *
     * @static
     * @param {Uint8Array} strBuffer UTF-8 Uint8Array.
     * @returns {String} base64 str
     * @memberof Crypt
     */
    static arrayBufferToBase64(strBuffer) {
        return base64js.fromByteArray(strBuffer)
    }

    /**
     * crypt base64 stringa to utf8 byteArray
     *
     * @static
     * @param {String} base64 str
     * @returns {Uint8Array} strBuffer UTF-8 Uint8Array.
     * @memberof Crypt
     */
    static base64ToArrayBuffer(base64) {
        return base64js.toByteArray(base64)
    }
}

// sm4
const UINT8_BLOCK = 16

const Sbox = Uint8Array.from([
    0xd6, 0x90, 0xe9, 0xfe, 0xcc, 0xe1, 0x3d, 0xb7, 0x16, 0xb6, 0x14, 0xc2, 0x28, 0xfb, 0x2c, 0x05,
    0x2b, 0x67, 0x9a, 0x76, 0x2a, 0xbe, 0x04, 0xc3, 0xaa, 0x44, 0x13, 0x26, 0x49, 0x86, 0x06, 0x99,
    0x9c, 0x42, 0x50, 0xf4, 0x91, 0xef, 0x98, 0x7a, 0x33, 0x54, 0x0b, 0x43, 0xed, 0xcf, 0xac, 0x62,
    0xe4, 0xb3, 0x1c, 0xa9, 0xc9, 0x08, 0xe8, 0x95, 0x80, 0xdf, 0x94, 0xfa, 0x75, 0x8f, 0x3f, 0xa6,
    0x47, 0x07, 0xa7, 0xfc, 0xf3, 0x73, 0x17, 0xba, 0x83, 0x59, 0x3c, 0x19, 0xe6, 0x85, 0x4f, 0xa8,
    0x68, 0x6b, 0x81, 0xb2, 0x71, 0x64, 0xda, 0x8b, 0xf8, 0xeb, 0x0f, 0x4b, 0x70, 0x56, 0x9d, 0x35,
    0x1e, 0x24, 0x0e, 0x5e, 0x63, 0x58, 0xd1, 0xa2, 0x25, 0x22, 0x7c, 0x3b, 0x01, 0x21, 0x78, 0x87,
    0xd4, 0x00, 0x46, 0x57, 0x9f, 0xd3, 0x27, 0x52, 0x4c, 0x36, 0x02, 0xe7, 0xa0, 0xc4, 0xc8, 0x9e,
    0xea, 0xbf, 0x8a, 0xd2, 0x40, 0xc7, 0x38, 0xb5, 0xa3, 0xf7, 0xf2, 0xce, 0xf9, 0x61, 0x15, 0xa1,
    0xe0, 0xae, 0x5d, 0xa4, 0x9b, 0x34, 0x1a, 0x55, 0xad, 0x93, 0x32, 0x30, 0xf5, 0x8c, 0xb1, 0xe3,
    0x1d, 0xf6, 0xe2, 0x2e, 0x82, 0x66, 0xca, 0x60, 0xc0, 0x29, 0x23, 0xab, 0x0d, 0x53, 0x4e, 0x6f,
    0xd5, 0xdb, 0x37, 0x45, 0xde, 0xfd, 0x8e, 0x2f, 0x03, 0xff, 0x6a, 0x72, 0x6d, 0x6c, 0x5b, 0x51,
    0x8d, 0x1b, 0xaf, 0x92, 0xbb, 0xdd, 0xbc, 0x7f, 0x11, 0xd9, 0x5c, 0x41, 0x1f, 0x10, 0x5a, 0xd8,
    0x0a, 0xc1, 0x31, 0x88, 0xa5, 0xcd, 0x7b, 0xbd, 0x2d, 0x74, 0xd0, 0x12, 0xb8, 0xe5, 0xb4, 0xb0,
    0x89, 0x69, 0x97, 0x4a, 0x0c, 0x96, 0x77, 0x7e, 0x65, 0xb9, 0xf1, 0x09, 0xc5, 0x6e, 0xc6, 0x84,
    0x18, 0xf0, 0x7d, 0xec, 0x3a, 0xdc, 0x4d, 0x20, 0x79, 0xee, 0x5f, 0x3e, 0xd7, 0xcb, 0x39, 0x48
])

const CK = Uint32Array.from([
    0x00070e15, 0x1c232a31, 0x383f464d, 0x545b6269,
    0x70777e85, 0x8c939aa1, 0xa8afb6bd, 0xc4cbd2d9,
    0xe0e7eef5, 0xfc030a11, 0x181f262d, 0x343b4249,
    0x50575e65, 0x6c737a81, 0x888f969d, 0xa4abb2b9,
    0xc0c7ced5, 0xdce3eaf1, 0xf8ff060d, 0x141b2229,
    0x30373e45, 0x4c535a61, 0x686f767d, 0x848b9299,
    0xa0a7aeb5, 0xbcc3cad1, 0xd8dfe6ed, 0xf4fb0209,
    0x10171e25, 0x2c333a41, 0x484f565d, 0x646b7279
])

const FK = Uint32Array.from([
    0xa3b1bac6, 0x56aa3350, 0x677d9197, 0xb27022dc
])


class SM4 {
    /**
     * Creates an instance of SM4.
     * @param {Object} config
     * @memberof SM4
     */
    constructor(config) {
        let keyBuffer = Crypt.stringToArrayBufferInUtf8(config.key)
        if (keyBuffer.length !== 16) {
            throw new Error('key should be a 16 bytes string')
        }
        /**
         * key should be 16 bytes string
         * @member {Uint8Array} key
         */
        this.key = keyBuffer
        /**
         * iv also should be 16 bytes string
         * @member {Uint8Array} iv
         */
        let ivBuffer = new Uint8Array(0)
        if (config.iv !== undefined && config.iv !== null) {
            // need iv
            ivBuffer = Crypt.stringToArrayBufferInUtf8(config.iv)
            if (ivBuffer.length !== 16) {
                throw new Error('iv should be a 16 bytes string')
            }
        }
        this.iv = ivBuffer
        /**
         * sm4's encrypt mode
         * @member {Enum} mode
         */
        this.mode = 'cbc'
        if (['cbc', 'ecb'].indexOf(config.mode) >= 0) {
            // set encrypt mode. default is cbc
            this.mode = config.mode
        }
        /**
         * sm4's cipher data type
         * @member {Enum} outType
         */
        this.cipherType = 'base64'
        if (['base64', 'text'].indexOf(config.outType) >= 0) {
            // set encrypt mode. default is cbc
            this.cipherType = config.outType
        }
        /**
         * sm4's encrypt round key array
         * @member {Uint32Array} encryptRoundKeys
         */
        this.encryptRoundKeys = new Uint32Array(32)
        // spawn 32 round keys
        this.spawnEncryptRoundKeys()

        /**
         * sm4's decrypt round key array
         * @member {Uint32Array} encryptRoundKeys
         */
        this.decryptRoundKeys = Uint32Array.from(this.encryptRoundKeys)
        this.decryptRoundKeys.reverse()
    }

    /**
     * general sm4 encrypt/decrypt algorithm for a 16 bytes block using roundKey
     *
     * @param {Uint32Array} blockData
     * @param {Uint32Array} roundKeys
     * @return {Uint32Array} return a 16 bytes cipher block
     * @memberof SM4
     */
    doBlockCrypt(blockData, roundKeys) {
        let xBlock = new Uint32Array(36)
        xBlock.set(blockData, 0)
        // loop to process 32 rounds crypt
        for (let i = 0; i < 32; i++) {
            xBlock[i + 4] = xBlock[i] ^ this.tTransform1(xBlock[i + 1] ^ xBlock[i + 2] ^ xBlock[i + 3] ^ roundKeys[i])
        }
        let yBlock = new Uint32Array(4)
        // reverse last 4 xBlock member
        yBlock[0] = xBlock[35]
        yBlock[1] = xBlock[34]
        yBlock[2] = xBlock[33]
        yBlock[3] = xBlock[32]
        return yBlock
    }

    /**
     * spawn round key array for encrypt. reverse this key array when decrypt.
     * every round key's length is 32 bytes.
     * there are 32 round keys.
     * @return {Uint32Array}
     * @memberof SM4
     */
    spawnEncryptRoundKeys() {
        // extract mk in key
        let mk = new Uint32Array(4)
        mk[0] = this.key[0] << 24 | this.key[1] << 16 | this.key[2] << 8 | this.key[3]
        mk[1] = this.key[4] << 24 | this.key[5] << 16 | this.key[6] << 8 | this.key[7]
        mk[2] = this.key[8] << 24 | this.key[9] << 16 | this.key[10] << 8 | this.key[11]
        mk[3] = this.key[12] << 24 | this.key[13] << 16 | this.key[14] << 8 | this.key[15]
        // calculate the K array
        let k = new Uint32Array(36)
        k[0] = mk[0] ^ FK[0]
        k[1] = mk[1] ^ FK[1]
        k[2] = mk[2] ^ FK[2]
        k[3] = mk[3] ^ FK[3]
        // loop to spawn 32 round keys
        for (let i = 0; i < 32; i++) {
            k[i + 4] = k[i] ^ this.tTransform2(k[i + 1] ^ k[i + 2] ^ k[i + 3] ^ CK[i])
            this.encryptRoundKeys[i] = k[i + 4]
        }
    }

    /**
     * left rotate x by y bits
     *
     * @param {*} x
     * @param {Number} y
     * @returns
     * @memberof SM4
     */
    rotateLeft(x, y) {
        return x << y | x >>> (32 - y)
    }

    /**
     * L transform function for encrypt
     *
     * @param {Uint32Number} b
     * @returns {Uint32Number}
     * @memberof SM4
     */
    linearTransform1(b) {
        return b ^ this.rotateLeft(b, 2) ^ this.rotateLeft(b, 10) ^ this.rotateLeft(b, 18) ^ this.rotateLeft(b, 24)
    }

    /**
     * L' transform function for key expand
     *
     * @param {Uint32Number} b
     * @returns {Uint32Number}
     * @memberof SM4
     */
    linearTransform2(b) {
        return b ^ this.rotateLeft(b, 13) ^ this.rotateLeft(b, 23)
    }

    /**
     * τ transform function
     *
     * @param {Uint32Number} a
     * @returns {Uint32Number}
     * @memberof SM4
     */
    tauTransform(a) {
        return Sbox[a >>> 24 & 0xff] << 24 | Sbox[a >>> 16 & 0xff] << 16 | Sbox[a >>> 8 & 0xff] << 8 | Sbox[a & 0xff]
    }

    /**
     * mix replacement T transform for encrypt
     *
     * @param {Uint32Number} z
     * @returns {Uint32Number}
     * @memberof SM4
     */
    tTransform1(z) {
        let b = this.tauTransform(z)
        let c = this.linearTransform1(b)
        return c
    }

    /**
     * mix replacement T transform for key expand
     *
     * @param {Uint32Number} z
     * @returns {Uint32Number}
     * @memberof SM4
     */
    tTransform2(z) {
        let b = this.tauTransform(z)
        let c = this.linearTransform2(b)
        return c
    }

    /**
     * padding the array length to multiple of BLOCK
     *
     * @param {ByteArray} originalBuffer
     * @returns {ByteArray}
     * @memberof SM4
     */
    padding(originalBuffer) {
        if (originalBuffer === null) {
            return null
        }
        let paddingLength = UINT8_BLOCK - originalBuffer.length % UINT8_BLOCK
        let paddedBuffer = new Uint8Array(originalBuffer.length + paddingLength)
        paddedBuffer.set(originalBuffer, 0)
        paddedBuffer.fill(paddingLength, originalBuffer.length)
        return paddedBuffer
    }

    /**
     * depadding the byte array to its original length
     *
     * @param {ByteArray} paddedBuffer
     * @returns {ByteArray}
     * @memberof SM4
     */
    dePadding(paddedBuffer) {
        if (paddedBuffer === null) {
            return null
        }
        let paddingLength = paddedBuffer[paddedBuffer.length - 1]
        let originalBuffer = paddedBuffer.slice(0, paddedBuffer.length - paddingLength)
        return originalBuffer
    }

    /**
     * exctract uint32 array block from uint8 array
     *
     * @param {Uint8Array} uint8Array
     * @param {Number} baseIndex
     * @returns {Uint32Array}
     * @memberof SM4
     */
    uint8ToUint32Block(uint8Array, baseIndex = 0) {
        let block = new Uint32Array(4) // make Uint8Array to Uint32Array block
        block[0] = uint8Array[baseIndex] << 24 | uint8Array[baseIndex + 1] << 16 | uint8Array[baseIndex + 2] << 8 | uint8Array[baseIndex + 3]
        block[1] = uint8Array[baseIndex + 4] << 24 | uint8Array[baseIndex + 5] << 16 | uint8Array[baseIndex + 6] << 8 | uint8Array[baseIndex + 7]
        block[2] = uint8Array[baseIndex + 8] << 24 | uint8Array[baseIndex + 9] << 16 | uint8Array[baseIndex + 10] << 8 | uint8Array[baseIndex + 11]
        block[3] = uint8Array[baseIndex + 12] << 24 | uint8Array[baseIndex + 13] << 16 | uint8Array[baseIndex + 14] << 8 | uint8Array[baseIndex + 15]
        return block
    }

    /**
     * encrypt the string plaintext
     *
     * @param {String} plaintext
     * @memberof SM4
     * @return {String} ciphertext
     */
    encrypt(plaintext) {
        let plainByteArray = Crypt.stringToArrayBufferInUtf8(plaintext)
        let padded = this.padding(plainByteArray)
        let blockTimes = padded.length / UINT8_BLOCK
        let outArray = new Uint8Array(padded.length)
        if (this.mode === 'cbc') {
            // CBC mode
            if (this.iv === null || this.iv.length !== 16) {
                throw new Error('iv error')
            }
            // init chain with iv (transform to uint32 block)
            let chainBlock = this.uint8ToUint32Block(this.iv)
            for (let i = 0; i < blockTimes; i++) {
                // extract the 16 bytes block data for this round to encrypt
                let roundIndex = i * UINT8_BLOCK
                let block = this.uint8ToUint32Block(padded, roundIndex)
                // xor the chain block
                chainBlock[0] = chainBlock[0] ^ block[0]
                chainBlock[1] = chainBlock[1] ^ block[1]
                chainBlock[2] = chainBlock[2] ^ block[2]
                chainBlock[3] = chainBlock[3] ^ block[3]
                // use chain block to crypt
                let cipherBlock = this.doBlockCrypt(chainBlock, this.encryptRoundKeys)
                // make the cipher block be part of next chain block
                chainBlock = cipherBlock
                for (let l = 0; l < UINT8_BLOCK; l++) {
                    outArray[roundIndex + l] = cipherBlock[parseInt(l / 4)] >> ((3 - l) % 4 * 8) & 0xff
                }
            }
        } else {
            // this will be ECB mode
            for (let i = 0; i < blockTimes; i++) {
                // extract the 16 bytes block data for this round to encrypt
                let roundIndex = i * UINT8_BLOCK
                let block = this.uint8ToUint32Block(padded, roundIndex)
                let cipherBlock = this.doBlockCrypt(block, this.encryptRoundKeys)
                for (let l = 0; l < UINT8_BLOCK; l++) {
                    outArray[roundIndex + l] = cipherBlock[parseInt(l / 4)] >> ((3 - l) % 4 * 8) & 0xff
                }
            }
        }

        // cipher array to string
        if (this.cipherType === 'base64') {
            return Crypt.arrayBufferToBase64(outArray)
        } else {
            // text
            return Crypt.utf8ArrayBufferToString(outArray)
        }
    }

    /**
     * decrypt the string ciphertext
     *
     * @param {String} ciphertext
     * @memberof SM4
     */
    decrypt(ciphertext) {
        // get cipher byte array
        let cipherByteArray = new Uint8Array()
        if (this.cipherType === 'base64') {
            // cipher is base64 string
            cipherByteArray = Crypt.base64ToArrayBuffer(ciphertext)
        } else {
            // cipher is text
            cipherByteArray = Crypt.stringToArrayBufferInUtf8(ciphertext)
        }
        let blockTimes = cipherByteArray.length / UINT8_BLOCK
        let outArray = new Uint8Array(cipherByteArray.length)
        // decrypt the ciphertext by block
        if (this.mode === 'cbc') {
            // todo CBC mode
            if (this.iv === null || this.iv.length !== 16) {
                throw new Error('iv error')
            }
            // init chain with iv (transform to uint32 block)
            let chainBlock = this.uint8ToUint32Block(this.iv)
            for (let i = 0; i < blockTimes; i++) {
                // extract the 16 bytes block data for this round to encrypt
                let roundIndex = i * UINT8_BLOCK
                // make Uint8Array to Uint32Array block
                let block = this.uint8ToUint32Block(cipherByteArray, roundIndex)
                // reverse the round keys to decrypt
                let plainBlockBeforeXor = this.doBlockCrypt(block, this.decryptRoundKeys)
                // xor the chain block
                let plainBlock = new Uint32Array(4)
                plainBlock[0] = chainBlock[0] ^ plainBlockBeforeXor[0]
                plainBlock[1] = chainBlock[1] ^ plainBlockBeforeXor[1]
                plainBlock[2] = chainBlock[2] ^ plainBlockBeforeXor[2]
                plainBlock[3] = chainBlock[3] ^ plainBlockBeforeXor[3]
                // make the cipher block be part of next chain block
                chainBlock = block
                for (let l = 0; l < UINT8_BLOCK; l++) {
                    outArray[roundIndex + l] = plainBlock[parseInt(l / 4)] >> ((3 - l) % 4 * 8) & 0xff
                }
            }
        } else {
            // ECB mode
            for (let i = 0; i < blockTimes; i++) {
                // extract the 16 bytes block data for this round to encrypt
                let roundIndex = i * UINT8_BLOCK
                // make Uint8Array to Uint32Array block
                let block = this.uint8ToUint32Block(cipherByteArray, roundIndex)
                // reverse the round keys to decrypt
                let plainBlock = this.doBlockCrypt(block, this.decryptRoundKeys)
                for (let l = 0; l < UINT8_BLOCK; l++) {
                    outArray[roundIndex + l] = plainBlock[parseInt(l / 4)] >> ((3 - l) % 4 * 8) & 0xff
                }
            }
        }
        // depadding the decrypted data
        let depaddedPlaintext = this.dePadding(outArray)
        // transform data to utf8 string
        return Crypt.utf8ArrayBufferToString(depaddedPlaintext)
    }
}


// module.exports = SM4
export default SM4